Yea I definitely need square bellows for what I'm working on. Its one of my homebrew camera designs. Pulling them off of an old enlarger isn't a bad idea. I used to have several sitting around but tossed them last time we did a big cleaning.

The other option is make some it's not that difficult these are a set I made for my Quarter plate camera, a non tapering set is easier still. Total cost less than $10 and that's with materials left over for more.
I could just make them I suppose. Ian, can you reference any link that you got instructions or a pattern from and also the materials you used. I've made them before but used too thick material so they didn't work out that well.

Thanks to all for the help!